Answer
95% confidence interval for difference: $-128.47\ltµ_M-µ_W\lt-42.62$
We are 95% confident that the difference between the wait time at McDonald's and Wendy's is between -128.47 and -42.62 seconds.
He could claim that McDonald's customers normally wait from 1 to 2 minutes less than Wendy's customers.
Work Step by Step
In MINITAB, enter the McDonald’s values in C1 and the Wendy’s values in C2.
Select Stat -> Basic Statistics -> 2-Sample t
Select "Each sample is in its own column"
In Sample 1 enter C1 and in Sample 2 enter C2
Click in Options. Enter 95 in Confidence level, 0 in Hypothesized difference. In "Alternative hypothesis" select "Difference $\ne$ hypothesized difference". Click OK.
Click OK.
